1. Field of the Invention
This invention relates to a method for heat treatment of waste as well as an apparatus for implementing this method.
This invention concerns the field of waste treatment, more particularly that of the treatment of waste by heat, inside a heated chamber. This invention will have applications most particularly, but by no means limitatively, in the treatment of household, hospital or biohazardous waste.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Waste treatment methods of this type are already known, which consist of introducing waste into a bag before placing inside an apparatus designed to treat such waste a load consisting of the bag and the waste contained therein.
The method then consists, after placing the load inside the apparatus, of raising the temperature of the bottom and of the lid and then applying a hold temperature to this bottom and this lid, and therefore the load. Moreover, before this hold temperature is reached, the bottom and the lid are moved towards each other at least once and the load may be compacted.
For the implementation of the method, an apparatus is used, in particular one such as that described in U.S. Pat. No. 7,204,956, comprising a bottom and a lid incorporating heating means, which lead to an inhomogeneity of temperature inside the load. This inhomogeneity leads to the inhomogeneous and/or incomplete treatment of the waste (which is not acceptable for hospital or biohazardous waste) or requires, for an appropriate treatment of such waste, that the duration of the implementation of the method be extended substantially, which entails the consumption of a considerable amount of energy.
Moreover, this method consists of moving the bottom and the lid towards each other, and even compacting the load. Now, when the load contains a non-compactable object, the movement of the bottom and the lid towards each other is interrupted and the load is directly subjected to the hold temperature. The interruption of this movement of the bottom and of the lid leads to insufficient compaction of the load, which once again leads to an inhomogeneity of temperature inside this load with the same consequences as described above.
Furthermore and in spite of the movement of the bottom and the lid towards each other, the load usually contains a certain quantity of residual air, which causes poor conduction of the heat and therefore an inhomogeneity of temperature inside the load, again with the same consequences as described above.
Finally, the method involves allowing the air to be evacuated out of the apparatus, which then includes a filter designed to filter said evacuated air. Now, such a filter is particularly sensitive to the presence of liquids in the evacuated air, water in particular, which will render said filter totally inactive and will require it to be cleaned, and even removed. In order to overcome this drawback, the apparatus is equipped with means designed to detect the presence of such a liquid and to interrupt the waste treatment process if such a liquid is detected. Given that most waste will contain such a liquid, either the treatment of this waste will be rapidly interrupted, or the time during which the load is heated will have to be extended significantly, which, once again, will entail the consumption of a considerable amount of energy.